Coordination polymers of Mn(II) and Cu(II) orotate with 2-methylimidazole and N, N, N′, N′-tetramethylethylenediamine ligands: Syntheses, spectroscopic and thermal analyses and crystal structures of mer-[Mn(μ-HOr)(H 2O)(2-meim) 2] n and thermochromic {[Cu(μ-HOr)(tmen)] · 1.5H 2O} n complexes

Abstract

The syntheses, FT-IR and UV–Vis spectra, thermal analyses and crystal structures of Mn(II) and Cu(II) orotate coordination polymers with 2-methylimidazole (2-meim) and N,N,N′ ,N′-tetramethylethylenediamine (tmen) ligands are described. The orotate ligand acts as a bridging ligand with two different coordination modes, the { mer-[Mn(μ-HOr)(H 2O)(2-meim) 2]} n ( 1) complex displays an linear chain structure in which each Mn(II) ion exhibits a distorted octahedral coordination by a tridentate orotate, two 2-meim and one aqua ligand. In {[Cu(μ-HOr)(tmen)] · 1.5H 2O} n ( 2), the Cu(II) ion is coordinated by a tridentate orotate and one bidentate tmen ligand, and exhibits a square pyramidal geometry. These polymer chains are linked by hydrogen-bond interactions forming a three-dimensional network. Complex 2 exhibits an irreversible thermochromic effect. After dehydration, the color of the complex changes from blue to green.